Printed wiring board conductive via hole filler having metal oxide reducing capability

Abstract

A conductive via filler for printed wiring boards capable of reducing copper oxides and thereby eliminating a cleaning step in printed wiring board construction, the conductive via filler consisting essentially of silver flake, a resin, a hardener, and a titanate coupling compound. The filler or paste may further include one or more of a flexibilizer, a solvent, and/or an accelerator. It is a feature of the invention that extensive pre-cleaning of copper substrates is obviated.

I claim as my invention:  
     
       1. An electrically conductive composition for filling via holes in a printed circuit board, consisting essentially of: 
       silver;  
       a hardener;  
       a resin; and  
       a titanate coupling compound for removing copper oxides, wherein the titanate is selected from the group consisting of monoalkoxy titanate and neoalkoxy titanate.  
     
     
       2. The composition of  claim 1 , wherein the neoalkoxy titanate is neopentyl (diallyl) oxy, tri (dioctyl) pyro-phosphato titanate. 
     
     
       3. The composition of  claim 1 , wherein the neoalkoxy titanate is neopentyl (diallyl) oxy, tri (dodecyl) benzene-sulfonyl titanate. 
     
     
       4. The composition of  claim 1 , wherein the hardener is at least one hardener selected from the group consisting of amine hardeners, urea hardeners, acid anhydride hardeners, and aromatic amine hardeners. 
     
     
       5. The composition of  claim 1 , further consisting essentially of one or more of a flexibilizer, a solvent a coupling compound, and an accelerator. 
     
     
       6. The composition of  claim 1 , wherein the silver consisting essentially of silver flake. 
     
     
       7. The composition of  claim 1 , further consisting essentially of a flexibilizer. 
     
     
       8. The composition of  claim 1 , further consisting essentially of a solvent. 
     
     
       9. The composition of  claim 1 , further consisting essentially of an accelerator. 
     
     
       10. The composition of  claim 1 , wherein the mixture is mechanically stirred. 
     
     
       11. The composition of  claim 10 , wherein the compound is heated after being mechanically stirred. 
     
     
       12. The composition of  claim 1 , wherein the mixture is passed through a roll mill. 
     
     
       13. The composition of  claim 12 , wherein the mixture is heated after being passed through a roll mill. 
     
     
       14. The composition of  claim 1 , wherein the composition is formed by heating the mixture at a temperature in excess of 100 degrees Centigrade. 
     
     
       15. The composition of  claim 14 , wherein the composition is heated approximately 10 minutes.